Systems and methods of forming refractory metal nitride layers using disilazanes

ABSTRACT

A method of forming (and apparatus for forming) refractory metal nitride layers (including silicon nitride layers), such as a tantalum (silicon) nitride barrier layer, on a substrate by using a vapor deposition process with a refractory metal precursor compound, a disilazane, and an optional silicon precursor compound.

This is a divisional of application Ser. No. 10/229,802, filed Aug. 28,2002, now U.S. Pat. No. 6,794,284, which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to methods of forming refractory metal nitridelayers (including silicon nitride layers) on substrates using a vapordeposition process with a refractory metal halide (preferably, fluoride)precursor compound, a disilazane, and optionally a silicon precursorcompound. The formed refractory metal (silicon) nitride layers areparticularly useful as diffusion barriers for polysilicon substrates toreduce diffusion of oxygen, copper, or silicon.

BACKGROUND OF THE INVENTION

In integrated circuit manufacturing, microelectronic devices such ascapacitors are the basic energy storage devices in random access memorydevices, such as dynamic random access memory (DRAM) devices, staticrandom access memory (SRAM) devices, and ferroelectric memory (FERAM)devices. Capacitors typically consist of two conductors acting aselectrodes, such as parallel metal (e.g., platinum) or polysiliconplates, that are insulated from each other by a layer of dielectricmaterial.

Historically, silicon dioxide has generally been the dielectric materialof choice for capacitors. However, the continuous shrinkage ofmicroelectronic devices over the years has led to dielectric layersapproaching only 10 Å in thickness (corresponding to 4 or 5 molecules).To reduce current tunneling through thin dielectric layers, highdielectric metal-containing layers, such as Al₂O₃, TiO₂, ZrO₂, HfO₂,Ta₂O₅, (Ba,Sr)TiO₃, Pb(Zr,Ti)O₃ and SrBi₂Ti₂O₉, have been developed toreplace SiO₂ layers. However, these metal-containing layers can providehigh leakage paths and channels for oxygen diffusion, especially duringannealing Also, an undesirable interfacial layer of SiO₂ is frequentlycreated by oxidation of polysilicon during the annealing of thedielectric layer.

One way to address these problems is to deposit a thin, conductive,amorphous, metal nitride barrier layer on the substrate prior to thedeposition of the thin resistive metal oxide layer. For example,reactive metal silicon nitride barrier metal layers are used to protectpolysilicon from oxygen diffusion prior to applying very thin (i.e.,less than 10 Å) barium strontium titanate dielectric films.

Refractory metal nitrides and refractory metal silicon nitrides, such astitanium nitride (Ti—N), tantalum nitride (Ta—N), tungsten nitride(W—N), molybdenum nitride (Mo—N), titanium silicon nitride (Ti—Si—N),tantalum silicon nitride (Ta—Si—N) and tungsten silicon nitride(W—Si—N), are also useful as conductive barrier layers between siliconsubstrates and copper interconnects to reduce copper diffusion. Thiscopper diffusion has led to degradation of device reliability, causingsemiconductor manufacturers to turn toward other less conductive metals,such as aluminum and tungsten.

Further improvements in high temperature adhesion and diffusionresistance can be realized when about 4 to about 30 atom % silicon isincorporated to form a more amorphous metal silicon nitride layer.Examples of refractory metal silicon nitrides that are useful as barrierlayers include tantalum silicon nitride (Ta—Si—N), titanium siliconnitride (Ti—Si—N), and tungsten silicon nitride (W—Si—N).

Methods for using physical vapor deposition (PVD) methods, such asreactive sputtering, to form Ta—Si—N barrier layers are known. Hara etal., “Barrier Properties for Oxygen Diffusion in a TaSiN Layer,” Jpn J.Appl.-Phys., 36(7B), L893 (1997) describe noncrystalline, lowresistivity Ta—Si—N layers that acts as a barrier to oxygen diffusionduring high temperature annealing at 650° C. in the presence of 0 ₂. TheTa—Si—N layers are formed by using radio-frequency reactive sputteringwith pure Ta and Si targets on a 100 nm thick polysilicon layer. Layershaving relatively low silicon content, such asTa_(0.50)Si_(0.16)N_(0.34) are stated to have a desirable combination ofgood diffusion barrier resistance along with low sheet resistance. TheseTa—Si—N barrier layers have improved peel resistance over Ta—N barrierlayers during annealing conditions.

Lee et al., “Structural and chemical stability of Ta—Si—N thin filmbetween Si and Cu,” Thin Solid Films, 320:141–146 (1998) describeamorphous, ultra—thin (i.e., less than 100 Å) tantalum-silicon-nitrogenbarrier films between silicon and copper interconnection materials usedin integrated circuits. These barrier films suppress the diffusion ofcopper into silicon, thus improving device reliability. Barrier filmshaving compositions ranging from Ta_(0.43)Si_(0.04)N_(0.53) toTa_(0.60)Si_(0.11)N_(0.29) were deposited on silicon by reactivesputtering from Ta and Si targets in an Ar/N₂ discharge, followed bysputter-depositing copper films.

However, when PVD methods are used, the stoichiometric composition ofthe formed metal nitride and metal silicon nitride barrier layers suchas Ta—N and Ta—Si—N can be non-uniform across the substrate surface dueto different sputter yields of Ta, Si, and N. Due to the resulting poorlayer conformality, defects such as pinholes often occur in such layerscreating pathways to diffusion. As a result, the effectiveness of aphysically deposited diffusion barrier layer is dependent on the layerbeing sufficiently thick.

Vapor deposition processes such as chemical vapor deposition (CVD) andatomic layer deposition (ALD) processes are preferable to PVD processesin order to achieve the most efficient and uniform barrier layercoverage of substrate surfaces. There remains a need for a vapordeposition process to form refractory metal nitrides and refractorymetal silicon nitride barrier layers (especially Ta—N and Ta—Si—Nlayers) on substrates, such as semiconductor substrates or substrateassemblies.

SUMMARY OF THE INVENTION

This invention is directed to methods of using vapor depositionprocesses to deposit refractory metal (silicon) nitride layers (i.e.,refractory metal nitride and refractory metal silicon nitride layers) onsubstrates. The process involves combining one or more refractory metalhalide precursor compounds, one or more nitrogen precursor compounds(disilazanes), and optionally one or more silicon precursor compounds.

In one embodiment, the present invention provides a method of forming alayer on a substrate (preferably, in a process of manufacturing asemiconductor structure). The method includes: providing a substrate(preferably a semiconductor substrate or substrate assembly such as asilicon wafer); providing a vapor that includes one or more refractorymetal precursor compounds of the formula MY_(n) (Formula I), wherein Mis a refractory metal (e.g., Ti, Nb, Ta, Mo, and W), each Y isindependently a halogen atom (preferably, F, Cl, l, or combinationsthereof, and more preferably, F), and n is an integer selected to matchthe valence of the metal M (e.g., n=5 when M=Ta); providing a vapor thatincludes one or more disilazanes of the formula(R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), wherein each R is independently anorganic group, and x is 1 to 3; and directing the vapors that includethe one or more refractory metal precursor compounds and the one or moredisilazanes to the substrate to form a refractory metal nitride layer(e.g., tantalum nitride) on one or more surfaces of the substrate. Theresultant nitride layer (or silicon nitride layer) is typically suitablefor use as a diffusion barrier layer, which is particularly advantageouswhen the substrate includes a silicon-containing surface.

The present invention also provides a method of manufacturing a memorydevice. The method includes: providing a substrate (preferably asemiconductor substrate or substrate assembly) that includes asilicon-containing surface; providing a vapor that includes one or morerefractory metal precursor compounds of the formula MY_(n)(Formula 1),wherein M is a refractory metal, each Y is independently a halogen atom,and n is an integer selected to match the valence of the metal M;directing the vapor that includes the one or more precursor compounds ofthe Formula I to the substrate and allowing the one or more compounds tochemisorb on the silicon-containing surface; providing a vapor thatincludes one or more disilazanes of the formula(R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), wherein each R is independently anorganic group, and x is 1 to 3; directing the vapor that includes theone or more disilazanes to the substrate with the chemisorbed compoundsthereon to form a refractory metal nitride barrier layer on thesilicon-containing surface; providing a first electrode on the barrierlayer; providing a high dielectric material over at least a portion ofthe first electrode; and providing a second electrode over the highdielectric material.

Preferred methods of the present invention also include steps ofproviding a vapor that includes one or more silicon precursor compoundsand directing the vapor to the substrate to form a refractory metalsilicon nitride layer. Optionally, the methods can also provide one ormore reaction gases other than the disilazanes and silicon precursorcompounds and direct the one or more reaction gases to the substrate.Also, in certain embodiments, the methods can provide a vapor thatincludes one or more metal-containing precursor compounds of a formuladifferent from Formula I and direct this vapor to the substrate.

The present invention also provides a vapor deposition apparatus thatincludes: a vapor deposition chamber having a substrate positionedtherein; and one or more vessels that include one or more refractorymetal precursor compounds of the formula MY_(n)(Formula I), wherein M isa refractory metal, each Y is independently a halogen atom, and n is aninteger selected to match the valence of the metal M; and one or morevessels that include one or more disilazanes of the formula(R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), wherein each R is independently anorganic group, and x is 1 to 3. Optionally, the apparatus can includeone or more vessels with one or more silicon precursor compounds thereinand/or one or more reaction gases other than the disilazanes and siliconprecursor compounds therein.

The methods of the present invention can utilize a chemical vapordeposition (CVD) process, which can be pulsed, or an atomic layerdeposition (ALD) process (a self-limiting vapor deposition process thatincludes a plurality of deposition cycles, typically with purgingbetween the cycles). Preferably, the methods of the present inventionuse ALD. In one embodiment of an ALD process, the refractory metalnitride layer is formed by alternately introducing the one or morevaporized precursor compounds and one or more vaporized disilazanes intoa deposition chamber during each deposition cycle.

“Substrate” as used herein refers to any base material or constructionupon which a metal-containing layer can be deposited. The term“substrate” is meant to include semiconductor substrates and alsoinclude non-semiconductor substrates such as films, molded articles,fibers, wires, glass, ceramics, machined metal parts, etc.

“Semiconductor substrate” or “substrate assembly” as used herein refersto a semiconductor substrate such as a metal electrode, basesemiconductor layer or a semiconductor substrate having one or morelayers, structures, or regions formed thereon. A base semiconductorlayer is typically the lowest layer of silicon material on a wafer or asilicon layer deposited on another material, such as silicon onsapphire. When reference is made to a substrate assembly, variousprocess steps may have been previously used to form or define regions,junctions, various structures or features, and openings such ascapacitor plates or barriers for capacitors.

“Layer” as used herein refers to any metal-containing layer that can beformed on a substrate from the precursor compounds of this inventionusing a vapor deposition process. The term “layer” is meant to includelayers specific to the semiconductor industry, such as “barrier layer,”“dielectric layer,” and “conductive layer.” (The term “layer” issynonymous with the term “film” frequently used in the semiconductorindustry.) The term “layer” is also meant to include layers found intechnology outside of semiconductor technology, such as coatings onglass.

“Barrier layer” as used herein refers to a conductive, interfacial layerthat can reduce diffusion of ambient oxygen through a dielectric layerinto a semiconductor substrate (typically a polysilicon substrate) orcan reduce diffusion of one layer into another, such as a copperconductive layer into a semiconductor substrate (typically a polysiliconsubstrate). For this invention, the barrier layer is a tantalum nitrideor tantalum silicon nitride layer.

“Refractory metal” as defined by Webster's New Universal UnabridgedDictionary (1992) is a metal that is difficult to fuse, reduce, or work.For the purposes of this invention, the term “refractory metal” is meantto include the Group IVB metals (i.e., titanium (Ti), zirconium (Zr),hafnium (Hf)); the Group VB metals (i.e., vanadium (V), niobium (Nb),tantalum (Ta)); and the Group VIB metals (i.e., chromium (Cr),molybdenum (Mo) and tungsten (W)).

“Precursor compound” as used herein refers to refractory metal precursorcompounds, nitrogen precursor compounds, silicon precursor compounds,and other metal-containing precursor compounds, for example. A suitableprecursor compound is one that is capable of forming, either alone orwith other precursor compounds, a refractory metal-containing layer on asubstrate using a vapor deposition process. The resulting refractorymetal-containing layers also typically include nitrogen and optionallysilicon. Such layers are often useful as diffusion barrier layers (i.e.,barrier layers).

“Deposition process” and “vapor deposition process” as used herein referto a process in which a metal—containing layer is formed on one or moresurfaces of a substrate (e.g., a doped polysilicon wafer) from vaporizedprecursor compound(s). Specifically, one or more metal precursorcompounds are vaporized and directed to one or more surfaces of a heatedsubstrate (e.g., semiconductor substrate or substrate assembly) placedin a deposition chamber. These precursor compounds form (e.g., byreacting or decomposing) a non-volatile, thin, uniform, metal—containinglayer on the surface(s) of the substrate. For the purposes of thisinvention, the term “vapor deposition process” is meant to include bothchemical vapor deposition processes (including pulsed chemical vapordeposition processes) and atomic layer deposition processes.

“Chemical vapor deposition” (CVD) as used herein refers to a vapordeposition process wherein the desired layer is deposited on thesubstrate from vaporized metal precursor compounds and any reactiongases used within a deposition chamber with no effort made to separatethe reaction components. In contrast to a “simple” CVD process thatinvolves the substantial simultaneous use of the precursor compounds andany reaction gases, “pulsed” CVD alternately pulses these materials intothe deposition chamber, but does not rigorously avoid intermixing of theprecursor and reaction gas streams, as is typically done in atomic layerdeposition or ALD (discussed in greater detail below).

“Atomic layer deposition” (ALD) as used herein refers to a vapordeposition process in which numerous consecutive deposition cycles areconducted in a deposition chamber. Typically, during each cycle themetal precursor is chemisorbed to the substrate surface; excessprecursor is purged out; a subsequent precursor and/or reaction gas isintroduced to react with the chemisorbed layer; and excess reaction gas(if used) and by-products are removed. As compared to the one cyclechemical vapor deposition (CVD) process, the longer duration multi-cycleALD process allows for improved control of layer thickness byself-limiting layer growth and minimizing detrimental gas phasereactions by separation of the reaction components. The term “atomiclayer deposition” as used herein is also meant to include the relatedterms “atomic layer epitaxy” (ALE) (see U.S. Pat. No. 5,256,244(Ackerman)), molecular beam epitaxy (MBE), gas source MBE,organometallic MBE, and chemical beam epitaxy when performed withalternating pulses of precursor compound(s), reaction gas and purge(i.e., inert carrier) gas.

“Chemisorption” as used herein refers to the chemical adsorption ofvaporized reactive precursor compounds on the surface of a substrate.The adsorbed species are irreversibly bound to the substrate surface asa result of relatively strong binding forces characterized by highadsorption energies (>30 kcal/mol), comparable in strength to ordinarychemical bonds. The chemisorbed species are limited to the formation ofa monolayer on the substrate surface. (See “The Condensed ChemicalDictionary”, 10th edition, revised by G. G. Hawley, published by VanNostrand Reinhold Co., New York, 225 (1981)). The technique of ALD isbased on the principle of the formation of a saturated monolayer ofreactive precursor molecules by chemisorption. In ALD one or moreappropriate reactive precursor compounds are alternately introduced(e.g., pulsed) into a deposition chamber and chemisorbed onto thesurfaces of a substrate. Each sequential introduction of a reactiveprecursor compound is typically separated by an inert carrier gas purge.Each precursor compound co-reaction adds a new atomic layer topreviously deposited layers to form a cumulative solid layer. The cycleis repeated, typically for several hundred times, to gradually form thedesired layer thickness. It should be understood, however, that ALD canuse one precursor compound and one reaction gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a device structure including a refractory metal nitridediffusion barrier layer according to the present invention.

FIG. 2 is a structure showing a high dielectric capacitor including anelectrode having a refractory metal nitride diffusion barrier layeraccording to the present invention.

FIG. 3 is a perspective view of a vapor deposition coating systemsuitable for use in the method of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention provides methods of forming a metal-containinglayer on a substrate using a vapor deposition process with one or morerefractory metal halide precursor compounds, one or more nitrogenprecursor compounds (disilazanes), and optionally one or more siliconprecursor compounds. For the present invention, the metal-containinglayer is a refractory metal nitride layer, preferably, a refractorymetal silicon nitride layer. More preferably, the layer is a tantalumsilicon nitride barrier layer.

The layers or films formed can be in the form of refractory metalnitride-containing films or refractory metal silicon nitride-containingfilms, wherein the layer includes one or more refractory metal nitridesor refractory metal silicon nitrides optionally doped with other metals.Thus, the term “refractory metal (silicon) nitride” films or layersencompass refractory metal nitrides, refractory metal silicon nitrides(of all possible proportions of refractory metal, Si, and N), as well asdoped films or layers thereof (e.g., mixed metal (silicon) nitrides).Such mixed metal species can be formed using one or moremetal-containing precursor compounds of a formula different from Formula1, which can be readily determined by one of skill in the art.

The layers of the present invention are preferably conductive. That is,they preferably display an electrical resistivity of no more than about10 mΩ-cm. The layers of the present invention are typically useful asbarrier layers, particularly in the manufacture of semiconductorinterconnects. For example, tantalum silicon nitride is being consideredas a copper barrier, and is of great interest as a barrier between highdielectric constant oxides and silicon. The addition of silicon totantalum nitride yields a material that is resistant to crystallizationand therefore to diffusion of silicon and metal species via grainboundaries.

The substrate on which the metal-containing layer is formed ispreferably a semiconductor substrate or substrate assembly. Any suitablesemiconductor material is contemplated, such as for example,conductively doped polysilicon (for this invention simply referred to as“silicon”). A substrate assembly may also contain a layer that includesplatinum, iridium, rhodium, ruthenium, ruthenium oxide, titaniumnitride, silicon dioxide, aluminum, gallium arsenide, glass, etc., andother existing or to-be-developed materials used in semiconductorconstructions, such as dynamic random access memory (DRAM) devices andstatic random access memory (SRAM) devices, for example. Preferredsubstrates include a silicon-containing surface.

Substrates other than semiconductor substrates or substrate assembliescan be used in methods of the present invention. These include, forexample, fibers, wires, etc. If the substrate is a semiconductorsubstrate or substrate assembly, the layers can be formed directly onthe lowest semiconductor surface of the substrate, or they can be formedon any of a variety of the layers (i.e., surfaces) as in a patternedwafer, for example.

Refractory metal precursor compounds useful in the practice of thisinvention are of the formula MY_(n) (Formula I) wherein M is arefractory metal, and each Y is independently a halogen atom. Morepreferably, each Y is a fluorine atom. Preferably, M is a Group IVB (Ti,Zr, Hf), VB (V, Nb, Ta), or VIB (Cr, Mo, W) metal (also referred to asGroups 4, 5, and 6 of the Periodic Table). More preferably, M is Ti, Nb,Ta, Mo, or W. Most preferably, M is Ti or Ta. In Formula I, n is aninteger selected to match the valence of the metal M. For example, whenM is tantalum (or another pentavalent metal), n is 5. For particularlypreferred embodiments, the refractory metal precursor compound is atantalum precursor compound of the formula TaF₅.

Nitrogen precursor compounds useful in the practice of this inventionare volatile disilazanes of the formula(R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), wherein each R is independently anorganic group and x is 1 to 3. Preferably, each R is independently a(C1–6) organic group, and more preferably, a (C1–4) organic group.Preferably, the organic group is an organic moiety such as ethyl andmethyl. Particularly preferred examples of the disilazane includetetramethyldisilazane (TMDS), (CH₃)₂HSiNHSiH(CH₃)₂, andhexamethyldisilazane. Most preferably, the disilazane istetramethyldisilazane (TMDS).

These nitrogen sources are significant relative to ammonia because theyprovide conductive metal nitride films with tantalum precursors, whereasammonia does not. Further, processes using ammonia often lead to solidby-products that can result in detrimental particulates on the substrateor deposits on chamber walls or downstream piping.

Optional silicon precursor compounds (other than the disilazane) usefulin the practice of this invention include silane (SiH₄), disilane(Si₂H₆), halogenated silanes (preferably chlorinated silanes of theformula SiH_(r)Cl_(s) wherein r=1–4 and s=4-r), and organic silanes ofthe formula SiH_(p)R¹ _(q) wherein p=1–4, q=4-p, and each R¹ isindependently an organic group (preferably having up to six carbonatoms, more preferably up to two carbon atoms, and most preferably,being an organic moiety). Examples include silane (SiH₄), disilane(Si₂H₆), dichlorosilane (SiH₂Cl₂), trichlorosilane (SiHCl₃), andtrimethylsilane (SiH(CH₃)₃).

As used herein, the term “organic group” is used for the purpose of thisinvention to mean a hydrocarbon group that is classified as an aliphaticgroup, cyclic group, or combination of aliphatic and cyclic groups(e.g., alkaryl and aralkyl groups). In the context of the presentinvention, suitable organic groups for precursor compounds of thisinvention are those that do not interfere with the formation of ametal-containing layer using vapor deposition techniques. In the contextof the present invention, the term “aliphatic group” means a saturatedor unsaturated linear or branched hydrocarbon group. This term is usedto encompass alkyl, alkenyl, and alkynyl groups, for example. The term“alkyl group” means a saturated linear or branched monovalenthydrocarbon group including, for example, methyl, ethyl, n-propyl,isopropyl, t-butyl, amyl, heptyl, 2-ethylhexyl, dodecyl, octadecyl, andthe like. The term “alkenyl group” means an unsaturated, linear orbranched monovalent hydrocarbon group with one or more olefinicallyunsaturated groups (i.e., carbon-carbon double bonds), such as a vinylgroup. The term “alkynyl group” means an unsaturated, linear or branchedmonovalent hydrocarbon group with one or more carbon-carbon triplebonds. The term “cyclic group” means a closed ring hydrocarbon groupthat is classified as an alicyclic group, aromatic group, orheterocyclic group. The term “alicyclic group” means a cyclichydrocarbon group having properties resembling those of aliphaticgroups. The term “aromatic group” or “aryl group” means a mono- orpolynuclear aromatic hydrocarbon group. The term “heterocyclic group”means a closed ring hydrocarbon in which one or more of the atoms in thering is an element other than carbon (e.g., nitrogen, oxygen, sulfur,etc.).

As a means of simplifying the discussion and the recitation of certainterminology used throughout this application, the terms “group” and“moiety” are used to differentiate between chemical species that allowfor substitution or that may be substituted and those that do not soallow for substitution or may not be so substituted. Thus, when the term“group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withnonperoxidic O, N, or S atoms, for example, in the chain as well ascarbonyl groups or other conventional substituents. Where the term“moiety” is used to describe a chemical compound or substituent, only anunsubstituted chemical material is intended to be included. For example,the phrase “alkyl group” is intended to include not only pure open chainsaturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl,t-butyl, and the like, but also alkyl substituents bearing furthersubstituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl,halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group”includes ether groups, haloalkyls, nitroalkyls, carboxyalkyls,hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase “alkylmoiety” is limited to the inclusion of only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like.

Various precursor compounds can be used in various combinations,optionally with one or more organic solvents (particularly for CVDprocesses), to form a precursor composition. The precursor compounds maybe liquids or solids at room temperature (preferably, they are liquidsat the vaporization temperature). Typically, they are liquidssufficiently volatile to be employed using known vapor depositiontechniques. However, as solids they may also be sufficiently volatilethat they can be vaporized or sublimed from the solid state using knownvapor deposition techniques. If they are less volatile solids, they arepreferably sufficiently soluble in an organic solvent or have meltingpoints below their decomposition temperatures such that they can be usedin flash vaporization, bubbling, microdroplet formation techniques, etc.Herein, vaporized precursor compounds may be used either alone oroptionally with vaporized molecules of other precursor compounds oroptionally with vaporized solvent molecules, if used. As used herein,“liquid” refers to a solution or a neat liquid (a liquid at roomtemperature or a solid at room temperature that melts at an elevatedtemperature). As used herein, “solution” does not require completesolubility of the solid but may allow for some undissolved solid, aslong as there is a sufficient amount of the solid delivered by theorganic solvent into the vapor phase for chemical vapor depositionprocessing. If solvent dilution is used in deposition, the total molarconcentration of solvent vapor generated may also be considered as ainert carrier gas.

Solvents can be used with the metal—containing precursors if desired.The solvents that are suitable for this application (particularly for aCVD process) can be one or more of the following: aliphatic hydrocarbonsor unsaturated hydrocarbons (C3–C20, and preferably C5–C10, cyclic,branched, or linear), aromatic hydrocarbons (C5–C20, and preferablyC5–C10), halogenated hydrocarbons, silylated hydrocarbons such asalkylsilanes, alkylsilicates, ethers, polyethers, thioethers, esters,lactones, ammonia, amides, amines (aliphatic or aromatic, primary,secondary, or tertiary), polyamines, nitrites, cyanates, isocyanates,thiocyanates, silicone oils, alcohols, or compounds containingcombinations of any of the above or mixtures of one or more of theabove. The compounds are also generally compatible with each other, sothat mixtures of variable quantities of the precursor compounds will notinteract to significantly change their physical properties.

In the practice of this invention, one or more reaction gases other thanthe nitrogen and silicon precursor compounds described herein can beused if desired. These include, for example, NH₃, N₂H₄, B₂H₆, PH₃, andcombinations thereof. Typically, the reaction gases referred to hereindo not include metal-containing compounds.

The precursor compounds can be vaporized in the presence of an inertcarrier gas if desired. Additionally, an inert carrier gas can be usedin purging steps in an ALD process. The inert carrier gas is typicallyselected from the group consisting of nitrogen, helium, argon, andmixtures thereof. In the context of the present invention, an inertcarrier gas is one that is generally unreactive with the complexesdescribed herein and does not interfere with the formation of thedesired metal-containing film (i.e., layer).

The deposition process for this invention is a vapor deposition process.Vapor deposition processes are generally favored in the semiconductorindustry due to the process capability to quickly provide highlyconformal layers even within deep contacts and other openings. Chemicalvapor deposition (CVD) and atomic layer deposition (ALD) are two vapordeposition processes often employed to form thin, continuous, uniform,metal-containing (preferably, barrier) layers onto semiconductorsubstrates. Using either vapor deposition process, typically one or moreprecursor compounds are vaporized in a deposition chamber and optionallycombined with one or more reaction gases to form a metal-containinglayer onto a substrate. It will be readily apparent to one skilled inthe art that the vapor deposition process may be enhanced by employingvarious related techniques such as plasma assistance, photo assistance,laser assistance, as well as other techniques.

The final layer (preferably, a barrier layer) formed preferably has athickness in the range of about 10 Å to about 500 Å. More preferably,the thickness of the metal-containing layer is in the range of about 30Å to about 80 Å.

Chemical vapor deposition (CVD) has been extensively used for thepreparation of metal-containing layers, such as barrier layers, insemiconductor processing because of its ability to provide highlyconformal and high quality barrier layers at relatively fast processingtimes. The desired precursor compounds are vaporized and then introducedinto a deposition chamber containing a heated substrate with optionalreaction gases and/or inert carrier gases. In a typical CVD process,vaporized precursors are contacted with reaction gas(es) at thesubstrate surface to form a layer (e.g., barrier layer). The singledeposition cycle is allowed to continue until the desired thickness ofthe layer is achieved.

Typical CVD processes generally employ precursor compounds invaporization chambers that are separated from the process chamberwherein the deposition surface or wafer is located. For example, liquidprecursor compounds are typically placed in bubblers and heated to atemperature at which they vaporize, and the vaporized liquid precursorcompound is then transported by an inert carrier gas passing over thebubbler or through the liquid precursor compound. The vapors are thenswept through a gas line to the deposition chamber for depositing alayer on substrate surface(s) therein. Many techniques have beendeveloped to precisely control this process. For example, the amount ofprecursor material transported to the deposition chamber can beprecisely controlled by the temperature of the reservoir containing theprecursor compounds and by the flow of an inert carrier gas bubbledthrough or passed over the reservoir.

Preferred embodiments of the precursor compounds described herein areparticularly suitable for chemical vapor deposition (CVD). Thedeposition temperature at the substrate surface is preferably held at atemperature in a range of about 100° C. to about 600° C., morepreferably in the range of about 200° C. to about 500° C. The depositionchamber pressure is preferably maintained at a deposition pressure ofabout 0.1 torr to about 10 torr. The partial pressure of precursorcompounds in the inert carrier gas is preferably about 0.001 torr toabout 10 torr.

Several modifications of the CVD process and chambers are possible, forexample, using atmospheric pressure chemical vapor deposition, lowpressure chemical vapor deposition (LPCVD), plasma enhanced chemicalvapor deposition (PECVD), hot wall or cold wall reactors or any otherchemical vapor deposition technique. Furthermore, pulsed CVD can beused, which is similar to ALD (discussed in greater detail below) butdoes not rigorously avoid intermixing of precursor and reactant gasstreams. Also, for pulsed CVD, the deposition thickness is dependent onthe exposure time, as opposed to ALD, which is self-limiting (discussedin greater detail below).

A typical CVD process may be carried out in a chemical vapor depositionreactor, such as a deposition chamber available under the tradedesignation of 7000 from Genus, Inc. (Sunnyvale, Calif.), a depositionchamber available under the trade designation of 5000 from AppliedMaterials, Inc. (Santa Clara, Calif.), or a deposition chamber availableunder the trade designation of Prism from Novelus, Inc. (San Jose,Calif.). However, any deposition chamber suitable for performing CVD maybe used.

Alternatively, and preferably, the vapor deposition process employed isa multi-cycle ALD process. Typically, this process provides for optimumcontrol of atomic-level thickness and uniformity to the deposited layer(e.g., barrier layer) and to expose the metal precursor compounds tolower volatilization and reaction temperatures to minimize degradation.Typically, in an ALD process, each reactant is pulsed sequentially ontoa suitable substrate, typically at deposition temperatures of about 25°C. to about 400° C. (preferably about 150° C. to about 300° C.), whichis generally lower than presently used in CVD processes. Under suchconditions the film growth is typically self-limiting (i.e., when thereactive sites on a surface are used up in an ALD process, thedeposition generally stops), insuring not only excellent conformalitybut also good large area uniformity plus simple and accurate thicknesscontrol. Due to alternate dosing of the precursor compounds and/orreaction gases, detrimental vapor-phase reactions are inherentlyeliminated, in contrast to the CVD process that is carried out bycontinuous coreaction of the precursors and/or reaction gases. (SeeVehkamäki et al, “Growth of SrTiO₃ and BaTiO₃ Thin Films by Atomic LayerDeposition,” Electrochemical and Solid-State Letters, 2(10):504–506(1999)).

A typical ALD process includes exposing an initial substrate to a firstchemical species (e.g., refractory metal precursor compound of theformula MY_(n)) to accomplish chemisorption of the species onto thesubstrate. Theoretically, the chemisorption forms a monolayer that isuniformly one atom or molecule thick on the entire exposed initialsubstrate. In other words, a saturated monolayer. Practically,chemisorption might not occur on all portions of the substrate.Nevertheless, such an imperfect monolayer is still a monolayer in thecontext of the present invention. In many applications, merely asubstantially saturated monolayer may be suitable. A substantiallysaturated monolayer is one that will still yield a deposited layerexhibiting the quality and/or properties desired for such layer.

The first species is purged from over the substrate and a secondchemical species (e.g., a different compound of the formula MY_(n), ametal-containing precursor compound of a formula different than MY_(n),or a disilazane compound) is provided to react with the first monolayerof the first species. The second species is then purged and the stepsare repeated with exposure of the second species monolayer to the firstspecies. In some cases, the two monolayers may be of the same species.As an option, the second species can react with the first species, butnot chemisorb additional material thereto. That is, the second speciescan cleave some portion of the chemisorbed first species, altering suchmonolayer without forming another monolayer thereon. Also, a thirdspecies or more may be successively chemisorbed (or reacted) and purgedjust as described for the first and second species.

Purging may involve a variety of techniques including, but not limitedto, contacting the substrate and/or monolayer with a carrier gas and/orlowering pressure to below the deposition pressure to reduce theconcentration of a species contacting the substrate and/or chemisorbedspecies. Examples of carrier gases include N₂, Ar, He, etc. Purging mayinstead include contacting the substrate and/or monolayer with anysubstance that allows chemisorption by—products to desorb and reducesthe concentration of a contacting species preparatory to introducinganother species. The contacting species may be reduced to some suitableconcentration or partial pressure known to those skilled in the artbased on the specifications for the product of a particular depositionprocess.

ALD is often described as a self-limiting process, in that a finitenumber of sites exist on a substrate to which the first species may formchemical bonds. The second species might only bond to the first speciesand thus may also be self-limiting. Once all of the finite number ofsites on a substrate are bonded with a first species, the first specieswill often not bond to other of the first species already bonded withthe substrate. However, process conditions can be varied in ALD topromote such bonding and render ALD not self-limiting. Accordingly, ALDmay also encompass a species forming other than one monolayer at a timeby stacking of a species, forming a layer more than one atom or moleculethick.

The described method indicates the “substantial absence” of the secondprecursor (i.e., second species) during chemisorption of the firstprecursor since insignificant amounts of the second precursor might bepresent. According to the knowledge and the preferences of those withordinary skill in the art, a determination can be made as to thetolerable amount of second precursor and process conditions selected toachieve the substantial absence of the second precursor.

Thus, during the ALD process, numerous consecutive deposition cycles areconducted in the deposition chamber, each cycle depositing a very thinmetal-containing layer (usually less than one monolayer such that thegrowth rate on average is from about 0.2 to about 3.0 Angstroms percycle), until a layer of the desired thickness is built up on thesubstrate of interest. The layer deposition is accomplished byalternately introducing (i.e., by pulsing) refractory metal precursorcompound(s) and disilazane compound(s) into the deposition chambercontaining a semiconductor substrate, chemisorbing the precursorcompound(s) as a monolayer onto the substrate surfaces, and thenreacting the chemisorbed precursor compound(s) with the otherco-reactive precursor compound(s). The pulse duration of precursorcompound(s) and inert carrier gas(es) is sufficient to saturate thesubstrate surface. Typically, the pulse duration is from about 0.1 toabout 5 seconds, preferably from about 0.2 to about 1 second.

In comparison to the predominantly thermally driven CVD, ALD ispredominantly chemically driven. Accordingly, ALD is often conducted atmuch lower temperatures than CVD. During the ALD process, the substratetemperature is maintained at a temperature sufficiently low to maintainintact bonds between the chemisorbed precursor compound(s) and theunderlying substrate surface and to prevent decomposition of theprecursor compound(s). The temperature is also sufficiently high toavoid condensation of the precursor compounds(s). Typically thesubstrate temperature is kept within the range of about 25° C. to about400° C. (preferably about 150° C. to about 300° C.), which is generallylower than presently used in CVD processes. Thus, the first species orprecursor compound is chemisorbed at this temperature. Surface reactionof the second species or precursor compound can occur at substantiallythe same temperature as chemisorption of the first precursor or, lesspreferably, at a substantially different temperature. Clearly, somesmall variation in temperature, as judged by those of ordinary skill,can occur but still be a substantially same temperature by providing areaction rate statistically the same as would occur at the temperatureof the first precursor chemisorption. Chemisorption and subsequentreactions could instead occur at exactly the same temperature.

For a typical ALD process, the pressure inside the deposition chamber iskept at about 10⁻⁴ torr to about 1 torr, preferably about 10⁻⁴ torr toabout 0.1 torr. Typically, the deposition chamber is purged with aninert carrier gas after the vaporized precursor compound(s) have beenintroduced into the chamber and/or reacted for each cycle.

The inert carrier gas(es) can also be introduced with the vaporizedprecursor compound(s) during each cycle.

The reactivity of a precursor compound can significantly influence theprocess parameters in ALD. Under typical CVD process conditions, ahighly reactive compound may react in the gas phase generatingparticulates, depositing prematurely on undesired surfaces, producingpoor films, and/or yielding poor step coverage or otherwise yieldingnon-uniform deposition. For at least such reason, a highly reactivecompound might be considered not suitable for CVD. However, somecompounds not suitable for CVD are superior ALD precursors. For example,if the first precursor is gas phase reactive with the second precursor,such a combination of compounds might not be suitable for CVD, althoughthey could be used in ALD. In the CVD context, concern might also existregarding sticking coefficients and surface mobility, as known to thoseskilled in the art, when using highly gas-phase reactive precursors,however, little or no such concern would exist in the ALD context.

After layer formation on the substrate, an annealing process can beoptionally performed in situ in the deposition chamber in a nitrogenatmosphere or ammonia atmosphere. Preferably, the annealing temperatureis within the range of about 400° C. to about 1000° C. Particularlyafter ALD, the annealing temperature is more preferably about 400° C. toabout 750° C., and most preferably about 600° C. to about 700° C. Theannealing operation is preferably performed for a time period of about0.5 minute to about 60 minutes and more preferably for a time period ofabout 1 minute to about 10 minutes. One skilled in the art willrecognize that such temperatures and time periods may vary. For example,furnace anneals and rapid thermal annealing may be used, and further,such anneals may be performed in one or more annealing steps.

As stated above, the use of the complexes and methods of forming filmsof the present invention are beneficial for a wide variety of thin filmapplications in semiconductor structures. For example, such applicationsinclude capacitors such as planar cells, trench cells (e.g., doublesidewall trench capacitors), stacked cells (e.g., crown, V-cell, deltacell, multi-fingered, or cylindrical container stacked capacitors), aswell as field effect transistor devices.

Use of the barrier layers of the present invention in semiconductorconstructions shall be described generally with reference to FIGS. 1 and2.

FIG. 1 illustrates a structure 10 including a substrate assembly 11 anda refractory metal nitride diffusion barrier layer 13 according to thepresent invention formed on a surface 12 of the substrate assembly 11,e.g., a silicon containing surface. The structure 10 further includes aconductive layer 14 (e.g., a copper layer). The structure 10 isillustrative of the use of a refractory metal nitride diffusion barrierlayer for any application requiring an effective barrier layer, forexample, to prevent diffusion from a silicon containing surface. Inother words, the refractory metal nitride diffusion barrier layer 13 maybe used in the fabrication of semiconductor devices wherever it isnecessary to prevent the diffusion of one material to an adjacentmaterial. For example, the substrate assembly 11 may be representativeof a contact structure having an opening extending to a siliconcontaining surface. In such a structure, diffusion barriers are commonlyused in such openings to prevent undesirable reactions, such as thereaction of a conductive contact material, e.g, copper or aluminum, withthe silicon containing surface.

Further, for example, the refractory metal nitride diffusion barrierlayer 13 may be used in the formation of storage cell capacitors for usein semiconductor devices, e.g., memory devices. As further describedherein, the refractory metal nitride diffusion barrier layer is usedwithin a stack of layers forming an electrode of a capacitor, e.g., theother layers including layers formed of materials such as platinum,ruthenium oxide, etc. One skilled in the art will recognize that varioussemiconductor processes and structures for various devices, e.g., CMOSdevices, memory devices, etc., would benefit from the barriercharacteristics of the barrier layers of the present invention and in nomanner is the present invention limited to the illustrative embodimentsdescribed herein.

FIG. 2 shows a structure 50 including substrate assembly 52 (e.g., asilicon substrate) and capacitor structure 54 formed relative thereto.Capacitor structure 54 includes a first electrode 56, a second electrode60, and a high dielectric constant layer 58 interposed therebetween. Forexample, the dielectric layer may be any suitable material having adesirable dielectric constant, such as TiO₂, ZrO₂, HfO₂, Ta₂O₅,(Ba,Sr)TiO₃, Pb(Zr,Ti)O₃, or SrBi₂Ti₂O₉. With use of the high dielectricconstant layer 58, diffusion barrier properties of the electrodes isparticularly important. For example, to function well in a bottomelectrode of a capacitor structure, the electrode layer or electrodestack must act as an effective barrier to the diffusion of silicon,particularly due to the processes used to form the high dielectricconstant materials. Such diffusion barrier properties are required whenthe substrate assembly 52 includes a silicon-containing surface 53 uponwhich the capacitor is formed, e.g., polysilicon, silicon substratematerial, N-doped silicon, P-doped silicon, etc., since oxidation of thediffused silicon to form silicon dioxide may result in degradedcapacitance, e.g., capacitance for a memory device. In addition, theelectrode stack must act as an oxygen barrier (e.g., diffusion barrierlayer 62) to protect the silicon-containing surface under the stack fromoxidizing. The formation of the refractory metal nitride diffusionbarrier layer enhances the barrier properties of the stack.

A system that can be used to perform vapor deposition processes(chemical vapor deposition or atomic layer deposition) of the presentinvention is shown in FIG. 3. The system includes an enclosed vapordeposition chamber 110, in which a vacuum may be created using turbopump 112 and backing pump 114. One or more substrates 116 (e.g.,semiconductor substrates or substrate assemblies) are positioned inchamber 110. A constant nominal temperature is established for substrate116, which can vary depending on the process used. Substrate 116 may beheated, for example, by an electrical resistance heater 118 on whichsubstrate 116 is mounted. Other known methods of heating the substratemay also be utilized.

In this process, precursor compounds 160 (e.g., a refractory metalprecursor compound and a disilazane) are stored in vessels 162. Theprecursor compounds are vaporized and separately fed along lines 164 and166 to the deposition chamber 110 using, for example, an inert carriergas 168. A reaction gas 170 may be supplied along line 172 as needed.Also, a purge gas 174, which is often the same as the inert carrier gas168, may be supplied along line 176 as needed. As shown, a series ofvalves 180–185 are opened and closed as required.

The following examples are offered to further illustrate the variousspecific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention, so the scopeof the invention is not intended to be limited by the examples.

EXAMPLES Example 1

Pulsed Chemical Vapor Deposition of Tantalum Silicon Nitride

Using a pulsed CVD method, the following precursor compounds were pulsedfor 200 cycles in a deposition chamber as described in FIG. 3 containinga borophosphosilicate glass (BPSG) substrate, each cycle consisting ofpulses in the following order: (1) tantalum pentafluoride (Alfa Aesar,Ward Hill, Mass.), (2) tetramethyldisilazane (TMDS) (Sigma-AldrichChemical C., Milwaukee, Wis.), (3) tantalum pentafluoride and (4)disilane (VOC Gases). During each cycle, excess amounts of eachprecursor compound not chemisorbed were purged from the chamber afterchemisorption and prior to the introduction of the next precursorcompound using an argon sweep at 30 mL/min and a vacuum pump. Thesubstrate temperature was kept at approximately 320° C. throughout theentire deposition process.

At the end of the pulsed CVD process, a 1375 Å thick mirror-like layerof tantalum silicon nitride was formed. The layer contained about 54atom % tantalum, 24 atom % nitrogen, 10 atom % silicon, 8 atom % carbonand 4 atom % oxygen as determined by x-ray photoelectron spectroscopy(XPS) analysis after a sputter time of 1 minute. X-ray diffractionanalysis (XDA) showed the layer to be amorphous, as measured immediatelyafter the pulsed CVD process was completed and also after annealing innitrogen for 1 minute at 750° C. Resistivity of the layer was 300 μΩ-cm,before and after annealing for 1 minute at 750° C.

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein as follows.

1. A vapor deposition apparatus comprising: a vapor deposition chamberhaving a substrate positioned therein; one or more vessels comprisingone or more refractory metal precursor compounds of the formulaMY_(n)(Formula I), wherein M is a refractory metal, each Y isindependently a halogen atom, and n is an integer selected to match thevalence of the metal M; and one or more vessels comprising one or moredisilazanes of the formula (R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), whereineach R is independently an organic group, and x is 1 to
 3. 2. Theapparatus of claim 1 further comprising one or more vessels comprisingone or more silicon precursor compounds and optionally one or morevessels comprising one or more reaction gases other than the disilazanesand silicon precursor compounds.
 3. The apparatus of claim 1 wherein thevapor deposition chamber is a chemical vapor deposition chamber.
 4. Theapparatus of claim 1 wherein the vapor deposition chamber is an atomiclayer vapor deposition chamber.
 5. The apparatus of claim 1 wherein thesubstrate comprises a semiconductor substrate.
 6. The apparatus of claim1 wherein the substrate comprises a silicon-containing surface.
 7. Theapparatus of claim 1 wherein the substrate comprises a silicon wafer. 8.The apparatus of claim 1 wherein Y is independently selected from thegroup consisting of F, Cl, I, and combinations thereof.
 9. The apparatusof claim 1 wherein each Y is a fluorine atom.
 10. The apparatus of claim1 wherein M is selected from the group consisting of Ti, Nb, Ta, Mo, andW.
 11. The apparatus of claim 1 wherein M is tantalum and n is
 5. 12.The apparatus of claim 1 wherein each R is independently selected fromthe group consisting of a (C1–C6) organic group.
 13. The apparatus ofclaim 12 wherein each R is independently ethyl or methyl.
 14. Theapparatus of claim 13 wherein the disilazane is tetramethyldisilazane(TMDS), (CH₃)₂HSiNHSiH(CH₃)₂, or hexamethyldisilazane.
 15. The apparatusof claim 14 wherein the disilazane is tetramethyldisilazane.
 16. Theapparatus of claim 1 with the proviso that the one or more disilazanesare not hexamethyldisilazane.
 17. The apparatus of claim 2 wherein theone or more silicon precursor compounds comprises silane (SiH₄),disilane (Si₂H₆), halogenated silanes, and organic silanes of theformula SiH_(p)R¹ _(q) wherein p=1–4, q=4-p, and each R¹ isindependently an organic group having up to six carbon atoms.
 18. Theapparatus of claim 17 wherein each R¹ is independently an organic grouphaving up to two carbon atoms.
 19. The apparatus of claim 17 whereineach R¹ is independently an organic moiety.
 20. The apparatus of claim 2wherein the one or more silicon precursor compounds is selected from thegroup consisting of silane (SiH₄), disilane (Si₂H₆), dichlorosilane(SiH₂Cl₂), trichlorosilane (SiHCl₃), and trimethylsilane (SiH(CH₃)₃).21. The apparatus of claim 20 wherein the one or more reaction gasesother than the nitrogen and silicon precursor compounds comprises NH₃,N₂H₄, B₂H₆, PH₃, and combinations thereof.
 22. The apparatus of claim 21further comprising an inert carrier gas selected from the groupconsisting of nitrogen, helium, argon, and mixtures thereof.
 23. A vapordeposition apparatus comprising: a vapor deposition chamber; one or morevessels comprising one or more refractory metal precursor compounds ofthe formula MY_(n)(Formula I), wherein M is a refractory metal, each Yis independently a halogen atom, and n is an integer selected to matchthe valence of the metal M; and one or more vessels comprising one ormore disilazanes of the formula (R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x),wherein each R is independently an organic group, and x is 1 to
 3. 24.The apparatus of claim 23 further comprising one or more vesselscomprising one or more silicon precursor compounds and optionally one ormore vessels comprising one or more reaction gases other than thedisilazanes and silicon precursor compounds.
 25. The apparatus of claim23 wherein the vapor deposition chamber is a chemical vapor depositionchamber.
 26. The apparatus of claim 23 wherein the vapor depositionchamber is an atomic layer vapor deposition chamber.
 27. A vapordeposition apparatus comprising: a vapor deposition chamber; one or morevessels comprising one or more refractory metal precursor compounds ofthe formula MY_(n)(Formula I), wherein M is a refractory metal, each Yis independently a halogen atom, and n is an integer selected to matchthe valence of the metal M, with the proviso that M is not titanium; andone or more vessels comprising one or more disilazanes of the formula(R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), wherein each R is independently anorganic group, and x is 1 to
 3. 28. The apparatus of claim 27 with theproviso that Y is not a chlorine atom.
 29. A vapor deposition apparatuscomprising: a vapor deposition chamber; one or more vessels comprisingone or more refractory metal precursor compounds of the formulaMY_(n)(Formula I), wherein M is a refractory metal, each Y isindependently a halogen atom, and n is an integer selected to match thevalence of the metal M, with the proviso that Y is not a chlorine atom;and one or more vessels comprising one or more disilazanes of theformula (R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), wherein each R isindependently an organic group, and x is 1 to
 3. 30. A vapor depositionapparatus comprising: a vapor deposition chamber; one or more vesselscomprising one or more refractory metal precursor compounds of theformula MY_(n)(Formula I), wherein M is a refractory metal, each Y isindependently a halogen atom, and n is an integer selected to match thevalence of the metal M; and one or more vessels comprising one or moredisilazanes of the formula (R)_(x)H_(3−x)SiNHSi(R)_(x)H_(3−x), whereineach R is independently an organic group, and x is 1 to 3, with theproviso that the one or more disilazanes are not hexamethyldisilazane.31. The apparatus of claim 30 with the proviso that M is not titanium.32. The apparatus of claim 30 with the proviso that Y is not a chlorineatom.
 33. The apparatus of claim 32 with the proviso that M is nottitanium.